$$ \frac{\pi}{4} x-\frac{x^2}{4}+C $$

$$ \frac{\pi}{4} x-\frac{x^2}{2}+C $$

$$ \frac{\pi}{2} x-\frac{x^2}{4}+C $$

$$ \frac{\pi}{4}-\frac{x}{4}+C $$

$$ \frac{\log x}{x+1}-\log \left|\frac{x}{x+1}\right|+C $$

$$ -\frac{\log x}{x+1}+\log \left|\frac{x}{x+1}\right|+C $$

$$ -\frac{\log x}{x+1}-\log \left|\frac{x}{x+1}\right|+C $$

$$ \frac{\log x}{x+1}+\log \left|\frac{x+1}{x}\right|+C $$

$$ \frac{1}{4} \log \left|\frac{\sqrt{x^2+4}-2}{\sqrt{x^2+4}+2}\right|+C $$

$$ \frac{1}{4} \log \left|\frac{\sqrt{x^2+4}+2}{\sqrt{x^2+4}-2}\right|+C $$

$$ \frac{1}{2} \log \left|\frac{\sqrt{x^2+4}+2}{\sqrt{x^2+4}-2}\right|+C $$

$$ \frac{1}{2} \log \left|\frac{\sqrt{x^2+4}-2}{\sqrt{x^2+4}+2}\right|+C $$

$-\frac{3}{2} \cos 2 x+C$

$\frac{2}{3} x+C$

$x+C$

$\frac{3}{2} \sin 2 x+C$